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Dron JS, Wang J, McIntyre AD, Cao H, Robinson JF, Duell PB, Manjoo P, Feng J, Movsesyan I, Malloy MJ, Pullinger CR, Kane JP, Hegele RA. Partial LPL deletions: rare copy-number variants contributing towards severe hypertriglyceridemia. J Lipid Res 2019; 60:1953-1958. [PMID: 31519763 DOI: 10.1194/jlr.p119000335] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 09/09/2019] [Indexed: 01/31/2023] Open
Abstract
Severe hypertriglyceridemia (HTG) is a relatively common form of dyslipidemia with a complex pathophysiology and serious health complications. HTG can develop in the presence of rare genetic factors disrupting genes involved in the triglyceride (TG) metabolic pathway, including large-scale copy-number variants (CNVs). Improvements in next-generation sequencing technologies and bioinformatic analyses have better allowed assessment of CNVs as possible causes of or contributors to severe HTG. We screened targeted sequencing data of 632 patients with severe HTG and identified partial deletions of the LPL gene, encoding the central enzyme involved in the metabolism of TG-rich lipoproteins, in four individuals (0.63%). We confirmed the genomic breakpoints in each patient with Sanger sequencing. Three patients carried an identical heterozygous deletion spanning the 5' untranslated region (UTR) to LPL exon 2, and one patient carried a heterozygous deletion spanning the 5'UTR to LPL exon 1. All four heterozygous CNV carriers were determined to have multifactorial severe HTG. The predicted null nature of our identified LPL deletions may contribute to relatively higher TG levels and a more severe clinical phenotype than other forms of genetic variation associated with the disease, particularly in the polygenic state. The identification of novel CNVs in patients with severe HTG suggests that methods for CNV detection should be included in the diagnostic workup and molecular genetic evaluation of patients with high TG levels.
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Affiliation(s)
- Jacqueline S Dron
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada.,Departments of Biochemistry Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Jian Wang
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Adam D McIntyre
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Henian Cao
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - John F Robinson
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - P Barton Duell
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239
| | - Priya Manjoo
- Department of Medicine, Gordon and Leslie Diamond Centre, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - James Feng
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158
| | - Irina Movsesyan
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158
| | - Mary J Malloy
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158
| | - Clive R Pullinger
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158
| | - John P Kane
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada .,Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada.,Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
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Martucci F, Trivellin G, Korbonits M. Familial isolated pituitary adenomas: an emerging clinical entity. J Endocrinol Invest 2012; 35:1003-14. [PMID: 23310926 DOI: 10.1007/bf03346742] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Familial pituitary tumors are increasingly recognized. While some of these cases are related to wellknown syndromic conditions such as multiple endocrine neoplasia type 1 (MEN1) or Carney complex, others belong to the familial isolated pituitary adenoma (FIPA) patient group. The discovery of heterozygous, loss-of-function germline mutations in the gene encoding the aryl hydrocarbon receptor interacting protein (AIP) in 2006 has subsequently enabled the identification of a mutation in this gene in 20% of FIPA families and 20% of childhood-onset simplex soma- totroph adenomas. The exact mechanism by which the lack of AIP leads to pituitary adenomas is not clear. AIP mutations cause a low penetrance autosomal dominant disease with often a distinct phenotype characterized by young-onset, aggressive, large GH, mixed GH and PRL or PRL-secreting adenomas. This review aims to summarize currently available clinical data on AIP mutation-positive and negative FIPA patients.
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Affiliation(s)
- F Martucci
- Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London, UK
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Gilbert B, Rouis M, Griglio S, de Lumley L, Laplaud P. Lipoprotein lipase (LPL) deficiency: a new patient homozygote for the preponderant mutation Gly188Glu in the human LPL gene and review of reported mutations: 75 % are clustered in exons 5 and 6. ANNALES DE GENETIQUE 2001; 44:25-32. [PMID: 11334614 DOI: 10.1016/s0003-3995(01)01037-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We have investigated the lipoprotein lipase (LPL) gene of a 2-year-old patient presenting classical features of the familial LPL deficiency including undetectable LPL activity. DNA sequence analysis of exon 5 identified the patient as a homozygote for the Gly188Glu mutation, frequently involved in this disease. A review of cases of LPL deficiency with molecular study of the LPL gene showed a total number of 221 reported mutations involved in this disease. Gly188Glu was involved in 23.5 % of cases and 74.6 % of mutations were clustered in exons 5 and 6. Based on these observations, we propose a method of screening for mutations in this gene.
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Affiliation(s)
- B Gilbert
- Unité de génétique, hôpital Dupuytren, Limoges, France.
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Alberto FL, Figueiredo MS, Zago MA, Araújo AG, Dos-Santos JE. The Lebanese mutation as an important cause of familial hypercholesterolemia in Brazil. Braz J Med Biol Res 1999; 32:739-45. [PMID: 10412552 DOI: 10.1590/s0100-879x1999000600009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Familial hypercholesterolemia (FH) is a common autosomal disorder that affects about one in 500 individuals in most Western populations and is caused by a defect in the low-density-lipoprotein receptor (LDLr) gene. In this report we determined the molecular basis of FH in 59 patients from 31 unrelated Brazilian families. All patients were screened for the Lebanese mutation, gross abnormalities of the LDLr gene, and the point mutation in the codon 3500 of the apolipoprotein B-100 gene. None of the 59 patients presented the apoB-3500 mutation, suggesting that familial defective ApoB-100 (FDB) is not a major cause of inherited hypercholesterolemia in Brazil. A novel 4-kb deletion in the LDLr gene, spanning from intron 12 to intron 14, was characterized in one family. Both 5' and 3' breakpoint regions were located within Alu repetitive sequences, which are probably involved in the crossing over that generated this rearrangement. The Lebanese mutation was detected in 9 of the 31 families, always associated with Arab ancestry. Two different LDLr gene haplotypes were demonstrated in association with the Lebanese mutation. Our results suggest the importance of the Lebanese mutation as a cause of FH in Brazil and by analogy the same feature may be expected in other countries with a large Arab population, such as North American and Western European countries.
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Affiliation(s)
- F L Alberto
- Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil
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Thorn JA, Needham EW, Mattu RK, Stocks J, Galton DJ. The Ser447–Ter mutation of the lipoprotein lipase gene relates to variability of serum lipid and lipoprotein levels in monozygotic twins. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)33904-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Arnault F, Etienne J, Noé L, Raisonnier A, Brault D, Harney JW, Berry MJ, Tse C, Fromental-Ramain C, Hamelin J, Galibert F. Human lipoprotein lipase last exon is not translated, in contrast to lower vertebrates. J Mol Evol 1996; 43:109-15. [PMID: 8660435 DOI: 10.1007/bf02337355] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have sequenced the first fish (zebrafish, Brachydanio rerio) lipoprotein lipase (LPL) cDNA clone. Similarities were found in mammalian LPL cDNA, but the codon spanning the last two exons (which is thus split by the last intron) is AGA (Arg) as opposed to TGA in mammals. Exon 10 is thus partially translated. These results were confirmed with rainbow trout (Oncorhynchus mykiss). We also investigated whether mammal TGA coded for selenocystein (SeCys), the 21st amino acid, but found that this was not the case: TGA does not encode SeCys but is a stop codon. It thus appears that the sense codon AGA (fish) has been transformed into a stop codon TGA (human) during the course of evolution. It remains to be determined if the "loss" of the C-terminal end of mammalian LPL protein has conferred an advantage in terms of LPL activity or, on the contrary, a disadvantage (e.g., susceptibility to diabetes or atherosclerosis).
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Affiliation(s)
- F Arnault
- Laboratoire de Biochimie et Biologie Moléculaire, Faculté de Médecine St-Antoine-Tenon, Paris, France
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Rouis M, Lohse P, Dugi KA, Lohse P, Beg OU, Ronan R, Talley GD, Brunzell JD, Santamarina-Fojo S. Homozygosity for two point mutations in the lipoprotein lipase (LPL) gene in a patient with familial LPL deficiency: LPL(Asp9–>Asn, Tyr262–>His). J Lipid Res 1996. [DOI: 10.1016/s0022-2275(20)37606-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
Lipoprotein lipase (LPL; E.C. 3.1.1.34) is a key enzyme in the metabolism of lipids. Many diseases, including obesity, coronary heart disease, chylomicronemia (pancreatitis), and atherosclerosis, appear to be directly or indirectly related to abnormalities in LPL function. Human LPL is a member of a superfamily of lipases that includes hepatic lipase and pancreatic lipase. These lipases are characterized by extensive homology, both at the level of the gene and the mature protein, suggesting that they have a common evolutionary origin. A large number of natural mutations have been discovered in the human LPL gene, which are located at different sites in the gene and affect different functions of the mature protein. There is a high prevalence of two of these mutations (207 and 188) in the Province of Québec, and one of them (207) is almost exclusive to the French-Canadian population. A study of these and other naturally occurring mutant LPL molecules, as well as those created in vitro by site-directed mutagenesis, indicate that the sequence of LPL is organized into multiple structural and functional units that act in concert in the normal enzyme. In this review, we discuss the interrelationships of LPL structure and its function, the molecular etiology of abnormal LPL in humans, and the clinical and therapeutic aspects of LPL deficiency.
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Affiliation(s)
- V Murthy
- Department of Biochemistry, Faculty of Medicine, Laval University, Ste-Foy, Québec, Canada
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